Lipogenesis and gluconeogenesis in isolated hepatocytes from laying and nonlaying will be studied. The source of carbon, whether glucose, glycogen, or lactate, for fatty acid synthesis will be established. The pathway for the production of NADPH for reductive biosynthesis of fatty acids will be determined and the relative roles of the pentose cycle, malic enzyme and other reactions to NADPH synthesis determined. The role of insulin and glucagon in gluconeogenesis, glycolysis and lipogenesis will be studied. The hormonal effects inducing the increase in fatty acid synthesis upon the onset of egglaying will be investigated.